Metabolism investigation of the peptide-drug conjugate LN005 in rats using UHPLCHRMS

LN005, as a peptide-drug conjugate (PDC), is a conjugate of the homing peptide VAP and doxorubicin (DOX). The exceptional targeting ability of the homing peptide VAP is directed toward glucose-regulated protein (GRP78), a highly expressed protein primarily found in the endoplasmic reticulum of various solid tumors. However, there are limited reports regarding the metabolism of peptide-drug conjugates (PDCs), and the in vivo metabolism of LN005 has yet to be investigated. After intravenous injection of 18 mg/kg LN005 in SD rats, biological samples including plasma, urine, fecal, and bile samples, were collected and analyzed by ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS). A total of 11 possible metabolites of LN005 were identified. Unchanged LN005 was found to be the main component in rat blood and urine, accounting for 46.46% and 63.79% of the total peak areas, respectively. M1057 was the most abundant metabolite in feces, accounting for 57.65% of the total peak area. Only one metabolite, M398, was identified in rat bile. The metabolism of LN005 is closely related to DOX, and the primary metabolic pathways involved oxidative deamination or hydrolysis, reductive glycosidic cleavage, hydrolytic glycosidic cleavage, and dehydrogenation.

Smart glypican-3-targeting peptide-chlorin e6 conjugates for targeted photodynamic therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly aggressive and lethal malignancy with poor prognosis, necessitating the urgent development of effective treatments. Targeted photodynamic therapy (PDT) offers a promising way to selectively eradicate tumor cells without affecting normal cells. Inspired by promising features of peptide-drug conjugates (PDCs) in targeted cancer therapy, herein a novel glypican-3 (GPC3)-targeting PDC-PDT strategy was developed for the precise PDT treatment of HCC. The GPC3-targeting photosensitizer conjugates were developed by attaching GPC3-targeting peptides to chlorin e6. Conjugate 8b demonstrated the ability to penetrate HCC cells via GPC3-mediated entry process, exhibiting remarkable tumor-targeting capacity, superior antitumor efficacy, and minimal toxicity towards normal cells. Notably, conjugate 8b achieved complete tumor elimination upon light illumination in a HepG2 xenograft model without harm to normal tissues. Overall, this innovative GPC3-targeting conjugation strategy demonstrates considerable promise for clinical applications for the treatment of HCC.

Design, synthesis and bioactivity evaluation of novel fusion peptides and their CPT conjugates inducing effective anti-tumor responses on HER2 positive tumors

Human epidermal growth factor receptor 2 (HER2) represents an ideal target for antibody drug development, abnormal expression of the HER2 gene is associated with multiple tumor types. Pertuzumab, as the first monoclonal antibody inhibitor of HER2 dimerization, has been FDA-approved for HER2-positive patients. In order to enhance the activity of HER2-targeted peptide-drug conjugates (PDCs) developed based on pertuzumab, a novel class of conjugates 1-9 was designed and synthesized by fusing the N-terminal peptide sequence of the second mitochondria-derived activator of caspases (SMAC) with P1, followed by conjugation with CPT molecules. Compound 4 exhibited excellent in vitro anti-tumor activity across the three HER2-positive cell lines, comparable to the activity of CPT. Apoptosis induction assays indicated that the synergistic effect of the SMAC sequence enhanced the pro-apoptotic activity of the conjugate. Western Blot analysis and Caspase activity studies validated the mechanism through which SMAC peptides, in synergy with CPT, enhance the activity of PDCs. In vivo studies demonstrated that compound 4 possesses superior anti-tumor activity compared to CPT and can effectively mitigate potential renal toxicity associated with free SMAC peptides. In conclusion, conjugate 4 exhibited excellent anti-tumor activity both in vitro and in vivo, offering potential for further development as a novel peptide-conjugated drug.

Advances in targeted therapy for pancreatic cancer

Pancreatic cancer (PC) represents a group of malignant tumours originating from pancreatic duct epithelial cells and acinar cells, and the 5-year survival rate of PC patients is only approximately 12%. Molecular targeted drugs are specific drugs designed to target and block oncogenes, and they have become promising strategies for the treatment of PC. Compared to traditional chemotherapy drugs, molecular targeted drugs have greater targeting precision, and they have significant therapeutic effects and minimal side effects. This article reviews several molecular targeted drugs that are currently in the experimental stage for the treatment of PC; these include antibody-drug conjugates (ADCs), aptamer-drug conjugates (ApDCs) and peptide-drug conjugates (PDCs). ADCs can specifically recognize cell surface antigens and reduce systemic exposure and toxicity of chemotherapy drugs. By delivering nucleic acid drugs to target cells, the targeting RNA of ApDCs can inhibit the expression or translation of mutated genes, thereby inhibiting tumour development. Moreover, PDCs can effectively penetrate tumour cells, and the peptide groups in PDCs preferentially target tumour cells with minimal side effects. In the targeted therapy of PC, molecular targeted drugs have very broad prospects, which provides new hope for the clinical treatment of PC patients and is worth further research.

Design, synthesis and bioactivity investigation of peptide-camptothecin conjugates as anticancer agents with a potential to overcome drug resistance

Camptothecin (CPT) is a natural plant alkaloid from Camptotheca that exhibits a potent anticancer activity. However, its continued utilization is hindered by drawbacks such as low water solubility and restricted tumor selectivity. Cationic anticancer peptides (CAPs) are generally soluble in water, and exhibit favorable selectivity against malignant cells. In previous study, we have reported a CAP termed KM8-Aib present conspicuous selective anticancer effect. Thus, it is postulated conjugating KM8-Aib with CPT might be a plausible approach to improve the defects of CPT. A series of peptide-CPT conjugates were synthesized and subjected to biological evaluation. Among these compounds, Kb-CC07 displayed the highest selective activity against a set of cancer cell lines including drug-resistant cells, showing the IC50 values in the 0.11-1.01 μM range which is 1.9-22.6 times better than that of CPT, and a wide therapeutic index of 124.5 (vs 5.3 for CPT). The water solubility of Kb-CC07 was also improved by ∼ 100 fold compared with CPT. Further investigation unraveled that Kb-CC07 could effectively penetrate across plasma membranes and delivered more CPT molecules into cancer cells, overcoming the drug-resistance result from efflux drug transporters on tumor surface. In vivo experiments supported that Kb-CC07 has excellent in vivo antiproliferative activity against drug-resistant tumors over CPT (tumor growth inhibition of 98.2% and 37.5% for Kb-CC07 and CPT, respectively, at 5 μmol·kg-1), and prompts CPT accumulation in tumor tissue rather than normal organs, thus producing limited toxicities. To sum up, coupling therapeutic agents to CAPs would be a potential strategy to conquer the shortcomings of anticancer drugs. Additionally, Kb-CC07 is suggested to be a promising anticancer candidate deserving further investigation.

Evaluation of LFA-1 Peptide-Methotrexate Conjugates in Modulating Endothelial Cell Inflammation and Cytokine Regulation

Interactions between vascular endothelial cells and inflammatory leukocytes are intermediated via cell adhesion molecules and they become one of the key events for vascular cell injury and development of atherosclerosis. This study evaluated the effects of MTX-peptide conjugates as anti-inflammatory agents on human coronary artery endothelial cells (HCAEC) and Molt-3 T cells. Cyclic peptides, cLABL and cLBEL, were derived from the α- and β-subunits of leukocyte function-associated antigen-1 (LFA-1), respectively. They interact with intercellular adhesion molecule-1 (ICAM-1) to inhibit LFA-1/ICAM-1-mediated homotypic or heterotypic T-cell adhesion. cLABL and cLBEL were linked to the anti-inflammatory drug, methotrexate (MTX), to produce MTX-cLABL and MTX-cLBEL conjugates. This study showed that peptides and MTX-peptide conjugates inhibited T cell adhesion to HCAEC monolayers while MTX alone did not. The conjugates, but not MTX, inhibited binding of anti-ICAM-1 monoclonal antibody (mAb) to ICAM-1 on the HCAEC. This indicates that conjugation of MTX to cLABL and cLBEL peptides did not dramatically change their binding properties to ICAM-1. The conjugates had relatively lower toxicity to cells compared to MTX alone, while they were more toxic than the parent peptides. At low concentrations, MTX, MTX-cLABL and MTX-cLBEL decreased production of IL-6 and IL-8 as inflammatory cytokines. In contrast, higher concentrations of the parent peptides compared to the conjugates were required to inhibit IL-6 and IL-8 productions. Overall, both MTX-cLABL and MTX-cLBEL were more active than both free-peptides. In addition, the conjugates were less toxic than MTX alone. In conclusion, the conjugate can selectively target MTX to ICAM-1-expressing cells to increase cell targeting and to lower MTX toxicity.

Modulating albumin-mediated transport of peptide-drug conjugates for antigen-specific Treg induction

The therapeutic potential of antigen-specific regulatory T cells (Treg) has been extensively explored, leading to the development of several tolerogenic vaccines. Dexamethasone-antigen conjugates represent a prominent class of tolerogenic vaccines that enable coordinated delivery of antigen and dexamethasone to target immune cells. The importance of nonspecific albumin association towards the biodistribution of antigen-adjuvant conjugates has gained increasing attention, by which hydrophobic and electrostatic interactions govern the association capacity. Using an ensemble of computational and experimental techniques, we evaluate the impact of charged residues adjacent to the drug conjugation site in dexamethasone-antigen conjugates (Dex-K/E4-OVA323, K: lysine, E: glutamate) towards their albumin association capacity and induction of antigen-specific Treg. We find that Dex-K4-OVA323 possesses a higher albumin association capacity than Dex-E4-OVA323, leading to enhanced liver distribution and antigen-presenting cell uptake. Furthermore, using an OVA323-specific adoptive-transfer mouse model, we show that Dex-K4-OVA323 selectively upregulated OVA323-specific Treg cells, whereas Dex-E4-OVA323 exerted no significant effect on Treg cells. Our findings serve as a guide to optimize the functionality of dexamethasone-antigen conjugate amid switching vaccine epitope sequences. Moreover, our study demonstrates that moderating the residues adjacent to the conjugation sites can serve as an engineering approach for future peptide-drug conjugate development.

A designed cyclic peptide based on Trastuzumab used to construct peptide-drug conjugates for its HER2-targeting ability

Human epidermal growth factor receptor 2 (HER2) has been recognized as an important therapeutic target for its overexpression in many cancers. Trastuzumab is a monoclonal antibody targeting HER2, which has been approved by FDA to treat HER2-positive cancer. In this research, cyclic peptide Cyclo-GCGPep1 was designed based on the binding mode between antibody and HER2 protein in silico, which has been confirmed possessing good affinity with HER2. Cyclo-GCGPep1 was also used to construct peptide-drug conjugates with Camptothecin. Biological evaluations demonstrated that Conjugate 1 has a good antiproliferative activity on SK-BR-3 and NCI-N87 cells. Conjugate 1 retained the pro-apoptotic and Topo I inhibitory ability of Camptothecin. Meanwhile, it has good targeting ability towards HER2-positive cells with the help of Cyclo-GCGPep1. It also has better permeability in the tumor spheroid model than Camptothecin. In summary, the design of cyclic peptide derived from antibody is of significance for the discovery of targeting peptides and Conjugate 1 is expected as a good therapeutic agent for HER2-positive cancers.

Source and exploration of the peptides used to construct peptide-drug conjugates

Peptide-drug conjugates (PDCs) are a class of novel molecules widely designed and synthesized for delivering payload drugs. The peptide part plays a vital role in the whole molecule, because they determine the ability of the molecules to penetrate the membrane and target to the specific targets. Here, we introduce the source of different kinds of cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs) that have been used or could be used in constructing PDCs as well as their latest application in delivering drugs. What's more, the approaches of developing CPPs and CTPs and the techniques to discover novel peptides are focused on and summarized in the review. This review aims to help relevant researchers fast understand the research status of peptides in PDCs and carry forward the process of novel peptides discovery.

The Current Role of Cell-Penetrating Peptides in Cancer Therapy

Cell-penetrating peptides (CPPs) are a heterogeneous class of peptides with the ability to translocate across the plasma membrane and to carry attached cargos inside the cell. Two main entry pathways are discussed, as direct translocation and endocytosis , whereas the latter is often favored when bulky cargos are added to the CPP. Attachment to the CPP can be achieved by means of covalent coupling or non-covalent complex formation, depending on the chemical nature of the cargo. Owing to their striking abilities the further development and application of CPP-based delivery strategies has steadily emerged during the past years. However, one main pitfall when using CPPs is their non-selective uptake in nearly all types of cells. Thus, one particular interest lies in the design of targeting strategies that help to circumvent this drawback but still benefit from the potent delivery abilities of CPPs. The following review aims to summarize some of these very recent concepts and to highlight the current role of CPPs in cancer therapy.